F-wave Studies Research Articles

P355 The assessment of electrophysiological studies in patients with restless legs syndrome

Objectives To investigate the spinal excitability changes in patients with restless legs syndrome (RLS). Methods Five patients who were diagnosed as RLS clinically and free off the L-dopa treatment and 6 healthy controls (HC) were recruited. The symptom severity scale for RLS was evaluated. The electrophysiological studies consisted of F-wave studies, cutaneous silent period (CSP) recorded from extensor digitorum brevis (EDB) and abductor pollicis brevis (APB) muscles, H reflex studies recorded from soleus muscle. H reflex recruitment curves with double stimulation and H reflex during 50 Hz vibrations to Achilles tendon (Hv) were measured. Results The mean symptom severity scale was 17,4. The nerve excitability parameters, F-wave studies were not different between groups. The CSP were tended to be shorter in duration in EBD muscle in RLS patients (27 ms) than in HC (35,5 ms). The inhibition of H reflex during vibration reduced in RLS patients (Hv/Hmax%: 83,2 in RLS patients, 63,6 in HC). H reflex recruitment curves showed similar effect in inhibition and facilitation in both groups. Discussion The results of this study might reveal the increased excitability in spinal level in RLS patients. The findings in H reflex recruitment curves may be related with the small number of patients in groups. These studies displaying the spinal excitability changes would improve our understanding in pathophysiology in RLS.

Sample size for the estimation of F-wave parameters in healthy volunteers and amyotrophic lateral sclerosis patients

Objective: The study aimed to investigate whether sample sizes of F-wave study differed according to different nerves, different F-wave parameters, and amyotrophic lateral sclerosis(ALS) patients or healthy subjects. Methods: The F-waves in the median, ulnar, tibial, and deep peroneal nerves of 55 amyotrophic lateral sclerosis (ALS) patients and 52 healthy subjects were studied to assess the effect of sample size on the accuracy of measurements of the following F-wave parameters: F-wave minimum latency, maximum latency, mean latency, F-wave persistence, F-wave chronodispersion, mean and maximum F-wave amplitude. A hundred stimuli were used in F-wave study. The values obtained from 100 stimuli were considered "true" values and were compared with the corresponding values from smaller samples of 20, 40, 60 and 80 stimuli. F-wave parameters obtained from different sample sizes were compared between the ALS patients and the normal controls. Results: Significant differences were not detected with samples above 60 stimuli for chronodispersion in all four nerves in normal participants. Significant differences were not detected with samples above 40 stimuli for maximum F-wave amplitude in median, ulnar and tibial nerves in normal participants. When comparing ALS patients and normal controls, significant differences were detected in the maximum (median nerve, Z=-3.560, P<0.01; ulnar nerve, t=5.019, P<0.01; tibial nerve, Z=-2.475, P<0.05; peroneal nerve, Z=-2.088, P<0.05)and mean F-wave latency (median nerve, Z=-3.243, P<0.01; ulnar nerve, t=3.876, P<0.01; tibial nerve, Z=-2.206, P<0.05; peroneal nerve, Z=-2.205, P<0.05)in all four nerves, F-wave chronodispersion (Z=-3.152, P<0.01)in the ulnar nerve, F-wave persistence in the median (Z=6.139, P<0.01)and ulnar nerves(Z=5.350, P<0.01), mean F-wave amplitude in the tibial nerve(t=2.981, P<0.01), maximum F-wave amplitude in the ulnar (Z=-2.134, P<0.05)and tibial nerves (t=2.746, P<0.01)with 20 stimuli; for chronodispersion in tibial nerve (t=2.551, P<0.05)100 stimuli, for chronodispersion in peroneal nerve (Z=-2.086, P<0.05)80 stimuli, for F-wave persistence in tibial nerve (Z=2.119, P<0.05) 60 stimuli, for mean F-wave amplitude in ulnar (Z=-2.552, P<0.05)and peroneal nerve (Z=-2.228, P<0.05)40 stimuli, for maximum F-wave amplitude in peroneal nerve (t=2.693, P<0.01)60 stimuli were necessary to detect differences. Conclusions: Sample sizes of F-wave study differed according to different nerves, different F-wave parameters , and ALS patients or healthy subjects.

ID 4 – EMG in differential diagnosis of lumbosacral plexopathies

Introduction Lumbosacral plexus consists of ventral branches of roots L1-S4 and is divided in two relatively separate portions. The lumbar plexus originates in L1, L2, L3 and part of L4 and frequently receives contribution from Th12. The sacral plexus consists of lower branch L4 and ventral branches L5-S4. EMG examination of lumbal and sacral plexopathies often yields suboptimal results. Electrodiagnosis of lumbal plexopathy relies on needle EMG. Routine motor and sensory nerve conductions studies are unavailable for most of its terminal branches. For the sacral plexopathy the motor and sensory amplitudes of the peroneal, tibial, ischiadicus and suralis nerve may help by showing axonal involvement. Conversely, reduced nerve conduction velocities can point to a more diffuse demyelinating neuropathy. Aim Evaluation of the role of various neurophysiological methods in diagnostic work up in various lumbosacral plexopathies. Methods In motor nerve conduction studies not only common stimulations points but also proximal root stimulation with use of magnetic coil can be exploited. In sensory nerve conduction studies the needle stimulation or needle registration is an option. For diagnosis of plexus or root lesion F-wave studies or H-reflex (also for femoral nerve) can be used. Somatosensory evoked potentials may be important for setting the diagnosis. Not only distal – easy accessible – muscles, but also proximal and paraspinal muscles should be investigated. Results Some typical case reports are displayed with clinical findings and neuroimaging correlates (diabetic radiculo-plexopathy, autoimmune lumbosacral plexopathy, neoplastic, traumatic, ischemic and inflammatory plexopathies). Conclusion EMG has an important role in differential diagnostics of plexopathies. The use of various electrodiagnostic methods demand broad spectre of skills in EMG laboratory and deep knowledge of individual plexopathies.

Value of F-wave studies on the electrodiagnosis of carpal tunnel syndrome

BackgroundF waves are late electrophysiological responses to antidromic activation of motor neurons and are used to evaluate the conduction along the whole length of peripheral nerves. We aimed to determine the diagnostic efficacies of minimum median nerve F-wave latency (FWL) and median-to-ulnar nerve F-wave latency difference (FWLD) on carpal tunnel syndrome (CTS).Materials and methodsThe electrophysiological studies consisted of sensory and motor nerve conduction and F-wave studies of the median and ulnar nerves. The best cut-off points of minimum median nerve FWL and FWLD for the diagnosis of CTS were detected for the whole study group and for different height subgroups (Group 1: 150–159 cm, Group 2: 160–169 cm, and Group 3: over 170 cm). The diagnostic efficacies of minimum median nerve FWL and FWLD were calculated for the whole CTS group and for the mild CTS group, separately.ResultsThe best cut-off point of minimum median nerve FWL on the diagnosis of CTS was determined as 24.60 ms for the whole group. It was 23.90 ms for Group 1, 24.80 ms for Group 2, and 28.40 ms for Group 3. The usage of these stratified cut-off points yielded a higher total diagnostic efficacy rate than single cut-off point usage (79.9% vs 69%, respectively; P=0.02). The best cut-off point of FWLD on the diagnosis of CTS was 0.80 ms for the whole group. It was 0.55 ms for Group 1, 0.30 ms for Group 2, and 0.85 ms for Group 3. Both the single cutoff point usage and the stratified chart usage for FWLD had equal diagnostic efficacy (85.1%). In the mild CTS group, diagnostic efficacy was 55.5% for minimum median nerve FWL and 78.8% for FWLD (P=0.0001).ConclusionMedian-to-ulnar nerve FWLD yields a higher diagnostic efficacy than minimum median nerve FWL on the diagnosis of CTS. However, the sensitivities of both parameters are not satisfactory for the extremities with mild CTS, which compose the main group having diagnostic challenge.

Neuroplasticity and Brachial Plexus Injury

Traumatic damage to the brachial plexus is associated with temporary or permanent motor and sensory dysfunction of the upper extremity. It may lead to the severe disability of the patient, often excluded from the daily life activity. The pathomechanism of brachial plexus injury usually results from damage detected in structures taking origin in the rupture, stretching or cervical roots avulsion from the spinal cord. Often the complexity of traumatic brachial plexus injury requires a multidisciplinary diagnostic process including clinical evaluation supplemented with clinical neurophysiology methods assessing the functional state of its structures. Their presentation is the primary goal of this paper.The basis for the diagnosis of brachial plexus function is a clinical examination and neurophysiology studies: electroneurography (ENG), needle electromyography (EMG), somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) assessing the function of individual brachial plexus elements.The ENG and EMG studies clarify the level of brachial plexus damage, its type and severity, mainly using the Seddon clinical classification. In contrast to F-wave studies, the use of the MEPs in the evaluation of traumatic brachial plexus injury provides valuable information about the function of its proximal part. MEPs study may be an additional diagnostic in confirming the location and extent of the lesion, considering the pathomechanism of the damage. Clinical neurophysiology studies are the basis for determining the appropriate therapeutic program, including choice of conservative or reconstructive surgery which results are verified in prospective studies.

06-2 Effects of a whole body vibration as a means for controlling spasticity in post-stroke patients: A F-wave study

06-2 Effects of a whole body vibration as a means for controlling spasticity in post-stroke patients: A F-wave study

English

BACKGROUND: Diabetes mellitus (DM) is a metabolic disorder which has become a major public health problem worldwide. Its commonest complication is diabetic peripheral neuropathy (DPN). DPN is characterized by combining axonal loss and demyelinating sensory motor peripheral neuropathy. To investigate this condition nerve conduction studies with determination of latency and velocity are commonly used as they are considered to be the most sensitive, reliable, non- invasive and objective means. DPN is believed to affect mainly distal nerve segments. However, it has been recently reported that F-wave study in diabetic patients is very reliable. AIM: Aim of the present study was to find out whether F-wave minimal latency (FWML) is having more sensitivity compared to motor nerve conduction study for diagnosis of DPN. METHODS AND MATERIALS: Motor and sensory nerve conduction and F-wave studies of upper and lower extremity nerves were carried out bilaterally in 60 clinically diagnosed patients with Type II diabetes mellitus. These parameters were also studied in 45 age matched controls. RESULTS: Sensitivity for distal motor latency (DML) was 53.33% in median, 26.31% in ulnar, 25.8% in peroneal and 41.17% in tibial nerves. Sensitivity for motor amplitude- compound muscle action potential (CMAP) was 56.66% in the median, 66.66% in ulnar, 80.64% in personnel and 72.54% in tibial nerves. Sensitivity for motor conduction velocity (MNCV) was 50% in the median, 47.36% in ulnar, 77.41% in personnel and 72.55% in tibial nerves. Sensitivity for distal sensory latency (DSL) was 37.97% in the median, 23.8% in ulnar, 41.5% in sural nerves. Sensitivity for sensory amplitude (SNAP) was 8.01% in the median, 64.28% in ulnar and 60.37% in sural nerves. Sensitivity for sensory conduction velocity (SNCV) was 40.5% in median, 26.19% in ulnar and 58.49% in Sural nerves. Prolonged FWMLs were found in 73.87% of median, 69% of ulnar, 72.72% of peroneal and 68.96% of tibial nerves. The sensitivity for FWML was 75.7% in median, 81.37% in ulnar, 83.63% in peroneal and 81.7% in tibial nerve. CONCLUSION: FWML is a highly sensitive indicator for diagnosis of DPN.

F‐wave latencies in patients with diabetes mellitus

To evaluate the sensitivity of electrophysiologic assessments, we compared F-waves and motor and sensory nerve conduction studies (MNCS and SNCS) in patients with diabetes mellitus (DM). We tested median, ulnar, tibial, and fibular nerves in 132 DM patients divided into those with and without clinical evidence of polyneuropathy. Of 64 asymptomatic patients, 2 (3%) had MNCS or SNCS abnormalities, both of whom had F-wave changes, whereas 21 (33%) had only delayed F-waves, for a combined yield of 23 (36%). The corresponding values for 68 symptomatic patients consisted of 43 (63%), 14 (21%), and 57 (84%). In both groups, F-wave latency had a higher (P<0.05) frequency of abnormality than MNCS in all nerves. F-wave study also surpassed SNCS in lower limb nerves. F-waves of the tibial and fibular nerves are the most sensitive measure to detect subclinical or overt diabetic polyneuropathy. Muscle Nerve 49: 804-808, 2014.

ホールドリラックスを利用したリラックスイメージが脊髄神経機能の興奮性に与える影響

ホールドリラックスを利用したリラックスイメージが脊髄神経機能の興奮性に与える影響

Utility of nerve conduction study in early diagnosis of carpal tunnel syndrome (CTS)

Background: Carpal tunnel syndrome (CTS) is the commonest median nerve entrapment neuropathy with preponderance in females. Aims & Objective: The present study was carried out for early conformation of clinically diagnosed patients of Carpal Tunnel Syndrome (CTS) by electrodiagnostic tests which include motor conduction, sensory conduction, and F-wave studies. Materials and Methods: Early confirmation of clinically suspected patients of CTS by performing electrodiagnostic tests of median and ulnar nerves. 100 subjects of age group 30-50 years (50 clinically suspected patients of CTS, 50 as control group) were studied. Motor and Sensory conduction velocities, distal motor and sensory latencies and F wave latencies were performed using Medtronic Keypoint@ 2 EMG EP software. Results: Statistically significant (P

Dynamic F-Wave Study Aids in Diagnosis of Neurogenic Thoracic Outlet Syndrome

Neurogenic thoracic outlet syndrome (TOS) is a type of brachial plexopathy caused by recurrent microinjury in the region between the base of the neck and the armpit. Electrophysiologic diagnosis of TOS remains a challenge [1]. A number of electrodiagnostic approaches have been explored including nerve conduction studies (NCS), electromyography (EMG), and C8 nerve root stimulation [2-4]. Abnormal findings of medial antebrachial sensory in NCS and denervation changes in C8-T1 myotomeson EMG may provide electrophysiologic evidence to support the diagnosis [2,3,5]. Unfortunately, the frequency of the electrodiagnostic yield is usually low. Use of routine F-wave study and somatosensory evoked potential are of limited value [5-7]. Imaging studies including ultrasound, MRI, or CT angiography may show pathology in severe cases, but in early stages sensitivity of such testing is low [8]. Recently, CuevasTrisan and Cruz-Jimenez reported that provocative F waves may help in early diagnosis [9]. However, no significant changes in provocative F waves in the diagnosis of nonspecific neurogenictype thoracic outlet syndrome were lately reported, indicating absence of acceptable sensitivity in this regard [10]. Here we report that measurements of the mean latency difference in dynamic F-wave study may increase the diagnostic sensitivity and aid in the diagnosis of TOS.

Electrophysiological assessment of hand elevation test in the diagnosis of carpal tunnel syndrome

Provided that the hand elevation test can reproduce the symptoms of carpal tunnel syndrome (CTS), this phenomenon prompted the idea of developing a simple test to diagnose CTS. The aim of this study was assess the electrophysiological values of the hand elevation test in the diagnosis of CTS syndrome. Thirty patients with initial symptoms and clinical signs of CTS in 49 hands were included. Special provocative tests for CTS were carried out before the hand elevation tests and the electrophysiological studies at least 5 min to avoid their effect on the intended test. The hand elevation test was performed and the test result was considered positive if symptoms occurred within 2 min. Nerve conduction study, including motor and sensory nerve conduction studies with F-wave study for both median nerves, was performed twice immediately before and after the hand elevation provocative test. This study was carried out on 60 hands; however, the initial complaint was in 49 hands, where the results showed a highly significant difference in parasthesia and hand pain, values of nerve conduction study (distal motor and sensory latencies) both before and after the hand elevation test, and a nonsignificant difference in the F-wave latencies. The posthand elevation distal motor and sensory latencies showed a sensitivity of 100 versus 78.6%, a specificity of 75 versus 81.2%, a positive predictive value of 77.8 versus 78.6%, and a negative predictive value of 100 versus 81.2%, respectively. Hand elevation is a simple provocative test that could be the physical examination of choice and can be used as a first-order provocative test instead of other tests for the diagnosis of CTS. Its significant provocative value was documented electrophysiologically.

The Comparison of Multiple F-wave Variable Studies and Magnetic Resonance Imaging Examinations in the Assessment of Cervical Radiculopathy

The aims of this study were to investigate the correlation of the findings of multiple median and ulnar F-wave variables and magnetic resonance imaging examinations in the prediction of cervical radiculopathy. The data of 68 patients who underwent both nerve conduction studies of the upper extremities and cervical spine magnetic resonance imaging within 3 mos of the nerve conduction studies were retrospectively reviewed and reinterpreted. The associations between multiple median and ulnar F-wave variables (including persistence, chronodispersion, and minimal, maximal, and mean latencies) and magnetic resonance imaging evidence of lower cervical spondylotic radiculopathy (i.e., C7, C8, and T1 radiculopathy) were investigated. Patients with lower cervical radiculopathy exhibited reduced right median F-wave persistence (P = 0.011), increased right ulnar F-wave chronodispersion (P = 0.041), and a trend toward increased left ulnar F-wave chronodispersion (P = 0.059); however, there were no other consistent significant differences in the F-wave variables between patients with and patients without magnetic resonance imaging evidence of lower cervical radiculopathy. In comparison with normal reference values established previously, the sensitivity and positive predictive value of F-wave variable abnormalities for predicting lower cervical radiculopathy were low. There was a low correlation between F-wave studies and magnetic resonance imaging examinations. The diagnostic utility of multiple F-wave variables in the prediction of cervical radiculopathy was not supported by this study.

Seasonal, Age &amp;amp; Gender Variation of Guillain Barre Syndrome in a Tertiary Referral Center in India

Background: Seasonal variation & gender preponderance have not been adequately studied in Guillain Barre Syndrome (GBS). University of Health Sciences, Rohtak is the tertiary referral facility for a large part of North West India. We conducted a prospective study to investigate differences in GBS incidence between males and females & across different seasons of the year. Methods:65 clinically diagnosed GBS patients, aged 5 - 70 years, referred for nerve conduction, Fwave & EMG studies for 3 years. Results: 64.61% were males while 35.38% were females. Maximum patients were in the age group 5 - 20 years (46.15%). The highest incidence of GBS (41.53%) were seen in the summer months; 19 (29.23%) in the spring season, 11 (16.92%) in winter season and 8 (12.30%) in rainy season. 5 patients had diarrhoea while 12 patients had flu like syndrome 1 - 2 weeks before the onset of GBS. Conclusion: The peak seasonal clustering noted by us in the summer months was consistent significantly with other Asian studies. The age and sex distribution of GBS in our series, which showed children & minor preponderance with peak incidence in 5 - 20 years age followed by another in the age group 21 - 40 years, is different from most studies which report a second peak after 50 years of age.

Practical electrodiagnostic value of F-wave studies in chronic inflammatory demyelinating polyneuropathy

ObjectivesTo ascertain the practical electrodiagnostic value of F-waves in chronic inflammatory demyelinating polyneuropathy (CIDP). MethodsWe evaluated the diagnostic utility of F-waves in 18 prospectively-recruited patients with typical CIDP. Minimum/maximum/mean F-wave latencies, F-wave chronodispersion and F-wave persistence, were determined in median/ulnar/fibular/tibial nerves in patients and compared to controls with axonal neuropathy. ResultsAll latencies were significantly more delayed in CIDP patients. F-wave chronodispersion was significantly greater in median and ulnar nerves and F-wave persistence significantly more reduced in tibial nerves in CIDP patients. Use of these supplementary F-wave parameters was of value in identifying CIDP nerves. However F-wave studies were only of additional benefit to other demyelinating parameters in about 15% of all studied CIDP nerves. ConclusionsF-waves may be diagnostically helpful in CIDP in a minority of nerves without other nerve conduction abnormalities. Analysis of F-wave chronodispersion in upper limb nerves and possibly of F-wave persistence in tibial nerves, may add value to basic minimum F-wave latency studies. SignificanceThese results suggest F-wave analysis may not need to be systematic, for all nerves, in patients with suspected CIDP, especially those intolerant to electrical stimulation. Chronodispersion and persistence may be helpful parameters to consider in addition to minimum latency.

Modulation of motor cortex excitability by different levels of whole-hand afferent electrical stimulation

Objective In a previous transcranial magnetic stimulation (TMS) study we demonstrated that suprathreshold mesh-glove (MG) whole-hand stimulation elicits lasting changes in motor cortical excitability. Currently, there is no consensus with regard to the optimal parameters for the induction of sensorimotor cortical plasticity using peripheral electrical stimulation. Thus, in the present study we explore the modulatory effects of MG stimulation at different stimulus intensities and different frequencies in order to identify an optimal stimulation protocol. Methods MG stimulation was performed on 12 healthy subjects in separate sessions at different stimulation levels: sub-sensory at 50 Hz, sensory at 50 Hz and motor at 2 Hz. To verify if stimulation at lower frequencies is less effective, an additional experiment at sensory level with 2 Hz was performed. TMS was used to assess motor threshold (MT), motor evoked potentials (MEPs) recruitment curve (RC), short latency intracortical inhibition (SICI) and intracortical facilitation (ICF) to paired-pulse TMS at baseline ( T0), immediately after ( T1) and 1 h ( T2) after 30 min of MG stimulation. F-wave studies were performed to assess spinal motoneuron excitability. Results MG stimulation at sub-sensory/50 Hz and sensory/2 Hz level determines no significant cortical excitability changes; at sensory/50 Hz level and at motor/2 Hz level we found decreased MT, increased MEP RC as well as reduced SICI and increased ICF at T1 and T2. Conclusions MG stimulation at sensory/50 Hz and motor/2 Hz level induces similar long-lasting modulatory effects on motor cortical excitability. Both the strength of the corticospinal projections and the intracortical networks are influenced to the same extend. Significance The study provides further evidence that stimulation intensity and frequency can independently modulate motor cortical plasticity. The selection of optimal stimulation parameters has potentially important implications for the neurorehabilitation of patients after brain damage (e.g. stroke, traumatic brain injury) with hand motor deficits.

Impact of medical audit on electrodiagnostic medicine in polyneuropathy

Objective The aim of the study was to investigate whether experienced physicians’ electrodiagnostic practice and criteria can be influenced by international collaboration involving peer review medical audit. Methods Data was obtained from the ESTEEM project, an ongoing collaboration since 1991 among European neurophysiologists concerned with quality improvement in electrodiagnostic medicine. Three sets of the physicians’ polyneuropathy examinations performed with intervals of 2–4 years were analysed. Results Changes towards increased homogeneity among the physicians were found in (1) the average number of studies performed per patient and the number of abnormal studies required for accepting the diagnosis of polyneuropathy, with the most pronounced changes seen for abnormal motor nerve segments, abnormal F-wave studies, and electromyographic studies, and (2) the agreement on pathophysiological interpretation of nerve conduction studies and classification of polyneuropathy. Conclusions Changes towards increased homogeneity contributed to years of participation in peer review medical audit, were seen among a group of experienced physicians. Peer review medical audit as carried out here is however difficult to scale up. Therefore guidelines or minimal criteria should ideally supplement a medical audit process to disseminate the results obtained to a larger audience. Significance These results support the role of international peer review medical audit in quality improvement of electrodiagnostic medicine.

Motor nerve conduction study in cauda equina with high‐voltage electrical stimulation in multifocal motor neuropathy and amyotrophic lateral sclerosis

In this study we aim to establish a motor nerve conduction study (NCS) for the cauda equina and examine its usefulness in multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS). NCS of the tibial nerve proximal to the knee was performed with an optimized high-voltage electrical stimulation (HV-ES) method in 21 normal subjects, 5 with MMN, and 11 with ALS. HV-ES, but not magnetic stimulation, could supramaximally stimulate the cauda equina. Cauda equina motor conduction time determined by HV-ES, but not that with F-waves, correlated well with cauda equina length on magnetic resonance imaging. HV-ES revealed proximal lesions in 4 MMN patients but in none of the ALS patients. Importantly, 1 patient with "MMN without conduction block (CB)" had a CB in the cauda equina. Cauda equina motor conduction is better evaluated by HV-ES than with F-wave study or magnetic stimulation. HV-ES can help to distinguish MMN and "MMN without CB" from ALS.

P35-16 Beneficial effects of footbaths in controlling spasticity after stroke: F-wave study

P35-16 Beneficial effects of footbaths in controlling spasticity after stroke: F-wave study

SL17 Recent advances in F-wave studies

SL17 Recent advances in F-wave studies